A dust mask that tested positive for ricin also contained DNA from a Mississippi man suspected of sending poison-laced letters to President Barack Obama and others, an FBI agent testified Thursday.

The testimony came during a preliminary hearing for James Everett Dutshcke, 41, who was arrested Saturday at his home in Tupelo and charged with making ricin, the same substance mailed on April 8 to Obama, U.S. Sen. Roger Wicker and Lee County, Miss., judge Sadie Holland.

Magistrate Judge S. Allan Alexander ruled that there was enough probable cause to send the case to a grand jury. It’s not clear when one would hear evidence in this case.

Dutschke’s lawyer, George Lucas, waived a detention hearing, but reserved the right to ask for one later. That means Dutschke will remain behind bars for now.

FBI agent Stephen Thomason said that on April 22, agents saw Dutschke go to his former martial arts studio in Tupelo and then throw items in a trash can down the street. One of those items was a dust mask that tested positive for ricin, he said.

Thomason said the mask had DNA from two people on it.

He said Dustchke was the “major contributor.” The agent did not say who else’s DNA was on it.

Dutschke is second person to be charged in the case. The first suspect, Elvis impersonator Paul Kevin Curtis, 45, was arrested on April 17, but the charges were dropped six days later. After his arrest, Curtis said he was framed and identified Dutschke as someone who might have sent the letters, according to an FBI affidavit filed in federal court.

Curtis said he knows Dutschke and that they feuded over the years.

During Thursday’s hearing, Dutschke sat at the defendant’s table wearing an orange jail uniform. He scribbled notes at times and also shook his head in disagreement at some of the testimony.

No possible motive was discussed.

Much of Agent Thomason’s testimony was from an FBI affidavit made public earlier this week, which said trace amounts of ricin were found in Dutschke’s former martial arts studio.

Thomason said Dutschke used the Internet to make three purchases of castor beans, from which ricin is derived. The affidavit had said two, but Thomason said the investigation turned up another.

Lucas, Dutschke’s lawyer, said there was a way to make ricin in a way so that it isn’t deadly and repeatedly questioned the agent about tests performed on the substance in the letters.

“If it’s ricin, it’s deadly,” the agent said.

The FBI has not revealed details about how lethal the ricin was. A Senate official has said the ricin was not weaponized, meaning it wasn’t in a form that could easily enter the body. If inhaled, ricin can cause respiratory failure, among other symptoms. No antidote exists.

During the investigation, officials searched Dutschke’s home, business and minivans.

Thomason said documents from the home had printer markings similar to ones on letters sent to the officials.

Dutschke faces up to life in prison if convicted in the ricin case. He’s also facing unrelated charges of child molestation.